A storage apparatus to which Thin Provisioning (also referred to as Dynamic Provisioning) is applied is known. The storage apparatus generally provides a virtual logical volume (hereinafter referred to as a virtual volume) configured of multiple virtual pages, and comprises a pool configured of multiple actual pages. The storage apparatus, in case of writing data to an unassigned virtual page, assigns an actual page to the write destination virtual page from the pool, and writes the write target data to the assigned actual page. The virtual page is a virtual storage area, and the actual page is an actual storage area.
As the technologies related to this type of storage apparatus, for example, the technologies disclosed in the Patent Literatures 1 and 2 are known.
According to the Patent Literature 1, if the number of actual pages is zero, a physical storage device is added and, in accordance with the physical storage device, a logical disk is newly generated. By the logical disk being divided, actual pages which can be assigned are newly generated.
According to the Patent Literature 2, if the storage apparatus receives a write command from a host and if there is no actual page which can be assigned, fail is returned to the host. That is, the write is considered to have failed.